Necrotizing Fasciitis Caused by Cryptococcus gattii
Necrotizing fasciitis (NF) is a severe soft-tissue infection that can lead to high morbidity and mortality. The etiology of NF is often polymicrobial. Although rare, fungal organisms have been known to cause NF. Cryptococcus is a fungal infection that may lead to NF.
Here we report the case of a 73-year-old man who had diabetes and presented with pain and swelling in the left hand after being bitten by an insect over the dorsum of the hand. Operative débridement revealed NF caused by Cryptococcus gattii. Antifungal medication was started, and the patient underwent multiple débridements of the hand with subsequent skin grafting. Four months later, the hand wound was completely healed.
Authors have reported several cases of NF secondary to Cryptococcus neoformans in immunocompromised patients. The emerging C gattii pathogen affects immunocompetent patients. Although the transmission route is mainly respiratory, direct inoculation has been described as well.
Ours is the first reported case of NF secondary to C gattii. It is important to consider fungal elements as a source of NF. Appropriate treatment includes aggressive surgical débridement and antifungal therapy.
The literature includes 12 reported cases of NF secondary to Cryptococcus (Table 2), all C neoformans. Of these cases, 9 involved immunosuppression, and most of these patients were on long-term steroid treatment after organ transplantation. The most common infection site was the lower extremity. These cases of cryptococcal NF show that immunosuppression, and long-term steroid use in particular, is an important risk factor. The mortality rate for these reviewed cases was 41.6% (5/12). According to the literature, the mortality rates for patients with cryptococcal soft-tissue infections24 and posttransplant patients with cryptococcal NF21 were 37.5% and 60%, respectively. We believe the mortality rate in our reviewed cases likely was confounded by the fact that most of the patients were posttransplant patients on long-term immunosuppression.
Of the 12 patients, 5 had primary cutaneous disease. There seems to be no relationship between outcome and dissemination of disease. In addition, there is a paucity of literature on the effect of disseminated disease and cryptococcal soft-tissue infections. Therefore, no firm conclusions can be drawn regarding the effects of disseminated disease on severity of cryptococcal soft-tissue infection.
Treatment of cryptococcal NF involves a combination of surgical débridement and long-term antifungal therapy. Surgical débridement of NF includes delineating the extent of infection with complete surgical excision of the affected tissue.25 The aims of surgery should be to remove all unhealthy tissue, identify the offending organism, and plan for resurfacing or reconstruction of the afflicted extremity. Intraoperative-tissue histology should be performed to confirm the diagnosis of NF. Histology can be used to demonstrate cryptococcal infection. The diagnosis of cryptococcal infection can be aided with fungal cultures, and therefore we recommend that tissue cultures be sent not only for routine aerobic/anaerobic bacteria but also for mycobacteria and fungal organisms. Laboratory tests that aid in diagnosis include serum cryptococcal antigen titer.
The current treatment recommendation for cryptococcal disease in patients who are not HIV-positive or transplant hosts is amphotericin B deoxycholate 0.7 to 1.0 mg/kg/d plus flucytosine 100 mg/kg/d for at least 4 weeks.22 The regimen period may be shortened to 14 days for patients at low risk of treatment failure. Fluconazole should be given as maintenance therapy (200 mg/d) for 6 to 12 months. There is no compelling evidence for immunoglobulin therapy for cryptococcal disease.22
Conclusion
NF caused by Cryptococcus is rare. A high level of suspicion, and intraoperative specimens for histology and fungal microscopy and culture, can help in establishing the diagnosis. Molecular genotyping remains the diagnostic method of choice for NF secondary to Cryptococcus. Effective treatment consists of aggressive surgical débridement and antifungal therapy.
